Python 3 preparation: update calls to dict methods. Tool-assisted patch. Changes of iterkeys / itervalues / iteritems to keys / values / items are fully automated, but may make things less efficient in Python 2. Automated tools want to add list() around many calls to keys / values / items, but I thought most such list() additions were unnecessary because it seemed the result of keys / values / items was just iterated over while the set of dict keys remained unchanged, rather than used in a way requiring an actual list, or used while the set of keys in the dict could change. It's quite possible I missed some cases where list() was really needed, or left in some unnecessary list() calls. In cases where list() was only needed because the resulting list was then sorted in-place, I changed the code to use calls to sorted().

class MockNull:
    def __init__(self, **kwargs):
        for key, value in kwargs.items():
            self.__dict__[key] = value

    def __call__(self, *args, **kwargs): return MockNull()
    def __getattr__(self, name):
        # This allows assignments which assume all intermediate steps are Null
        # objects if they don't exist yet.
        #
        # For example (with just 'client' defined):
        #
        # client.db.config.TRACKER_WEB = 'BASE/'
        self.__dict__[name] = MockNull()
        return getattr(self, name)

    def __getitem__(self, key): return self
    def __nonzero__(self): return 0
    def __str__(self): return ''
    def __repr__(self): return '<MockNull 0x%x>'%id(self)
    def gettext(self, str): return str
    _ = gettext